KR910006586B1 - Magnetic recording media - Google Patents

Abstract

A magnetic recording medium is produced by mixing a magnetic powder with 3,4,5-trihydroxy benzonate cpd. of formula (I)[R= CnH2n+1; 8 <=n <=18 , dispersing the mixt. with a pigment compsn. to produce a magnetic layer soln, adding a hardening agent to the layer soln. to produce a magnetic pigment, and coating the pigment on the polyester base film. The cpd. (I) is pref. octyl gallate, lauryl gallate or cethyl gallate. The recording material has a good adesiveness and durability, and is used in magnetic tapes and magnetic disks.

Description

Magnetic recording media

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording medium. In particular, magnetic particles are uniformly dispersed in a binder due to improved dispersibility of a magnetic paint, and thus, magnetic particles dispersed in the binder are adhered to the binder so that the magnetic recording medium has excellent electron conversion characteristics and durability. It is about. The magnetic recording medium is roughly divided into a magnetic layer and a nonmagnetic support, and the magnetic layer is roughly divided into an inorganic component and an organic component. Inorganic components are mainly composed of magnetic particles, other small amounts of antistatic agents, abrasives, and the like, and organic components are hardeners, dispersants, lubricants, etc., mainly binders.

Magnetic particles are hydrophilic and adsorb gas, so they are inactive to organic compounds. Therefore, the dispersant should be used to make good mixing with the binder and the solution. Conventionally, as a method of improving the dispersibility of magnetic particles in a magnetic paint, a method of using a saturated or unsaturated fatty acid having a hydrophilic group at one end of a molecule as a dispersant and a lipophilic group at the other end (Japanese Patent Publication No. 44-18221, Japanese Patent Publication) 58-9488), a method using sorbic acid and sorbic acid derivatives (Japanese Patent Laid-Open No. 60-211621), a method using an epoxy compound having a benzene ring in a molecule (Japanese Patent Publication No. 60-211627) Uji diamine, which may be represented as C ₁₈ H ₃₇ (CH ₂ ) ₃ NH ₂ , or C ₁₇ H ₃₇ NH (CH ₂ ) ₃ NH ₂ and C ₁₇ H ₃₈ NH (CH ₂ ) ₃ NH. Method of using a mixture of Ujidiamine (Japanese Patent Laid-Open No. 60-263319), having the structure of R-NH (CH ₂ ) ₃ NH ₂ (where R represents a stearin group or a stearin group and olein group mixed) Method using a compound (JP-A 60-263324), Di having a hydrophilic group A method of using Diferpene (Japanese Patent Laid-Open No. 61-80526), a method of using polyvinyl pyrrolidone (Korean Patent No. 85-4836), an amine having a poly (carbonyl alkyleneoxy) chain, or Method of using a compound containing a salt with an acid thereof (Korean Patent No. 85-5852) As an organosilicon compound, Xn Si (OCH ₂ CH ₂ ) _m OR) _4-n (where n represents 1,2,3) m is 0,1, X is an alkylamino group, a vinyl group, a methacryl group, an epoxy group, R is an alkyl group) (Korean Patent No. 81-1122) and nitrocellulose as a dispersant and a binder A method using a linear saturated polyester and an acrylonitrile-butadiene copolymer (Korean Patent Publication No. 86-1477) and the like have been proposed.

However, such a conventional dispersant has a small dispersing effect of the magnetic particles in a small amount, and if the amount of the dispersing agent is increased to increase the dispersibility, the durability of the magnetic layer is lowered. The dispersion effect of is obtained, but the effect is not sufficiently satisfactory yet.

The present invention has been made to solve the above-mentioned problems and to improve the durability of the magnetic recording medium. In the magnetic recording medium having the magnetic layer on the nonmagnetic support, the magnetic recording medium has the following structure in the magnetic layer. A magnetic recording medium containing a, 4,5-trihydroxy benzoate compound.

n

18의 정수)Wherein R is CnH ₂ n + 1 and n is 8

n

Integer of 18)

The 3,4,5-trihydroxy benzoate compound used in the present invention is represented by octyl gallate, lauryl gallate, cetyl galate, and any of them may be used.

In the present invention, the amount of the 3,4,5-trihydroxy benzoate compound added is preferably 0.5 to 5.0 parts by weight based on 100 parts by weight of the magnetic powder in the magnetic layer. In this case, blooming occurs.

As a method of containing the 3,4,5-trihydroxy benzoate compound of the present invention in a magnetic layer, the above-mentioned material is added to a magnetic paint composed of magnetic powder, a binder component, and the like, which is coated on a nonmagnetic support to form a magnetic layer. The magnetic coating is prepared by dipping the magnetic particles in the surface of the magnetic particles by dipping the magnetic particles in a solution of the above method or by dissolving the above water in a suitable solvent such as alcohol, ether, or the like, followed by filtration and drying. And a method of applying this on a nonmagnetic support to form a magnetic layer.

In the case of the magnetic recording medium manufactured by the present invention, it can be seen that the adhesiveness and durability are extremely excellent due to the excellent electron conversion characteristics and the improved dispersibility of the magnetic coating, and also the surface or the back of the magnetic recording tape. The present invention can also be applied to magnetic discs and the like having a magnetic layer.

Example 1

Co-r-Fe ₂ O ₃ 100 parts by weight

120 parts by weight of a mixed solvent of toluene-methylethyl ketone-cyclohexanone (volume ratio 1: 1: 1)

4.5 parts by weight of alumina

The composition was used as the base composition, and 2.0 parts by weight of lauryl galart was added to the magnetic powder of the base composition, followed by mixing for 2 hours with a sand mill manufactured by DYNO-Mill, followed by dispersing for 4 hours by adding the following coating composition to the magnetic layer. After preparing the forming solution, the filter is passed through, and immediately before application, 4.0 parts by weight of Coronate L, manufactured by Japan Polyurethane Industries, Ltd., is added as a curing agent and stirred for 30 minutes.

9.0 parts by weight of polyurethane resin

12.5 parts by weight of nitro cellulose resin

4.5 parts by weight of carbon black (30% toluene dispersion)

Cyclohexanone 35.0 parts by weight

120.0 parts by weight of methyl ethyl ketone

Toluene 64.5 parts by weight

The magnetic coating thus prepared is applied onto a polyester base film having a thickness of 10 μm such that the thickness after drying is 4.5 μm, the magnetic field is oriented, and then dried and wound up. This was calendered and cut to 1/2 inch wide to make a sample tape.

Example 2

It carried out similarly to (Example 1) except having added 2.3 weight part of octyl gallats with respect to the magnetic powder of the basic composition of (Example 1).

Example 3

It carried out similarly to (Example 1) except having added 1.8 weight part of cetyl gallats with respect to the magnetic powder of the basic composition of (Example 1).

Comparative Example 1

A sample tape was prepared in the same manner as in (Example 1) using the basic composition of Example 1 as a magnetic paint.

Comparative Example 2

The basic composition of Example 1 was prepared in the same manner as in Example 1 except that 2.0 parts by weight of ethyl galate was added to the magnetic powder.

Comparative Example 3

The basic composition of Example 1 was prepared in the same manner as in Example 1 except that 2.0 parts by weight of Propyl Gallate was added to the magnetic powder.

The characteristics of the sample tapes made as the above examples and comparative examples are shown in the table below.

TABLE 1

* The sample is made in the shape of a disk and a scratch tester is used to evaluate the wear level of each sample, indicating that the wear level is low, high, and middle.

As shown in the above table, it can be seen that the magnetic recording medium using the dispersant according to the present invention can improve the glossiness, durability and coefficient of friction well, and also the magnetic properties and the electron conversion characteristics are good. On the other hand, as shown in the comparative example, when the above water is not used, it can be seen that the characteristics are significantly reduced.

Claims (2)

A magnetic recording medium having a magnetic layer on a nonmagnetic support, wherein the magnetic recording medium contains a 3,4,5-trihydroxy benzoate compound having the following structure in the magnetic layer.

(Wherein R can be represented as CnH ₂ n + 1 and n is 8

n

Integer of 18) The magnetic recording medium according to claim 1, wherein the amount of the 3,4,5-trihydroxy benzoate compound added is 0.5 to 5.0 parts by weight based on 100 parts by weight of the magnetic powder in the magnetic layer.